1. Field of the Invention
The present invention generally relates to pointer positioning devices and, more particularly, to an improved pointing device based on infrared light sources and detectors that is compact, rugged and ergonomically easy to use such as can be used in laptop computers and similar devices.
2. Background Description
The conventional mouse is a very useful device for moving the pointer on the computer displays and also for user input. However, for portable computers, it is desirable to provide a small compact input device which can provide the full functionality of the conventional mouse. Ergonomic convenience to the user is a paramount concern. Several types of pointer devices are currently available on different laptops and other portable computers. See S. Zhai, B. A. Smith, and T. Selker, "Improving Browsing Performance: A Study of Four Input Devices for Scrolling and Pointing Tasks," in Proceedings of INTERACT'97: The 6th IFIP Conference on Human-Computer Interaction, pp. 286-292, 1997; K. Kawachiya and H. Ishikawa, "NaviPoint: An Input Device for Mobile Information Browsing," Proceedings of Computer-Human Interaction CHI.98, 18-23 Apr. 1998, Los Angeles, pp. 1-8; and Microsoft Corp. Microsoft IntelliMouse Home Page at http://www.microsoft.com/products/hardware/mouse/intellimouse/default.htm.
A simple substitute for the conventional mouse found in earlier laptop computers is a miniature tracker ball which is based on electromechanical principles. Lower reliability, difficulty in holding a constant position and wear and tear during usage are the major drawbacks of this device. Another pointer device which is currently provided in IBM and other laptop computers is the TrackPoint.RTM. analog input device situated amidst keys on the keyboard. (TrackPoint is a registered trademark of IBM Corp.) See Rutledge, J. D. and Selker, "T Force-to-Motion Functions for Pointing," in Proceedings of INTERACT '90: The IFIP Conference on Human-Computer Interaction, pp. 701-705, 1990. This device is based on sensing the forces applied by the user's finger in the x and y directions. While this device is quite satisfactory in terms of pointing function, its use requires dexterity on the part of the user. For this reason, some users prefer laptops with other types of pointing devices. Another limitation of this device is that it does not support double-clicking function available with touch-pad type of pointing devices. The touch-pad pointing device is robust and easy to use. The touch-pad pointing device is currently available in many modern laptop computers. Here, the user moves his or her finger on rectangular area of the touch pad to move the pointer Although the touch-pad devices typically have one, two and sometimes three "mouse" buttons which allow single and double clicking, single-clicking and double-clicking effects can also be achieved by single and double hitter on the touch pad. Wear and tear of the touch pad and sensitivity to touch by different users or condition of the user's finger are some drawbacks of this device,